Over the long term, traditional eastern methods (such as meditation and yoga) train your brainwaves into balance. Of the newer methods, brainwave entrainment is an easy, low-cost method to temporarily alter your brainwave state. If you are trying to solve a particular difficulty or fine-tune your brainwave function, state-of-the-art brain training methods like neurofeedback and pEMF deliver targeted, quick, and lasting results.  

In the average person, the activity of one brain hemisphere is dominant over the other, called brain lateralization. This hemispheric imbalance leads us to experience the world in a black and white way, perceiving separation over connectedness. When brainwave entrainment is used to synchronize brainwave activity in both hemispheres simultaneously, a person can more easily integrate information from all parts of the brain and solve problems with greater intelligence and sensitivity.
The body responds in essentially the same way to made-up imagery as it does to real experiences. Positive, relaxing images can be an effective tool for relieving stress. Try it for yourself with this Guided Imagery podcast from our Founder and Director Dr. James Gordon, or check out Dr. Gordon’s book Unstuck: Your Guide to the Seven-Stage Journey Out of Depression for dozens more techniques, including scripts for guided imagery exercises.
Hi Jason, thanks for all the uploads to youtube. I’ve been using them in work recently to help me concentrate and relax. I like the music tracks that you’ve chosen to overlay the tones. A couple of times in the last 2 weeks I’ve experienced the wavy pulse like sound, similar to the tones in my left ear. I wasn’t listening to tracks at the time or that day. It doesn’t last but it feels a bit strange. I wondered if I might have been listening to the tracks too loudly and that it was almost like a type of tinnitus. I’m curious to know if anyone has been in touch with you in the past to say they’ve had a similar experience?

The mantra technique as taught by Michael at Project Meditation is an excellent example of an outward technique. Since the vast majority of people have somewhat active minds, this mantra technique is a good bet for most of us. Even mantra techniques have some differences. Some require rigid concentration while others are more relaxed, such as Michael’s technique. There are some that use chanting which is helpful for a person whose mind is hyperactive.
American Heart Association: "Four Ways to Deal With Stress."; PubMed Central: "Psychosocial and Psychophysiological Effects of Human-Animal Interactions: The Possible Role of Oxytocin."; NIH News in Health: "Can Pets Keep You Healthy?"; Cleveland Clinic: "Want a Healthy Heart? Laugh More!"; HelpGuide.org: "Laughter Is the Best Medicine."; Association for Psychological Science: "Power Posing: Brief Nonverbal; Displays Affect Neuroendocrine; Levels and Risk Tolerance."; Harvard Business School: "Power Posing: Fake It Until you Make It."; IZA.org: "The Effect of Sexual Activity on Wages."
This depends on how ready your brain is to absorb the impact of the tones and how responsive it is. Most people experience a feeling of relaxation and calm right from the first session. The degree to which you feel these hinges on how well your brain reacts. Use it over a few days and you can experience unmistakable signs of stress reduction and improved clarity of mind. After a while, when you brain gets trained in allowing better communication between the right and left hemispheres, you will sense that the feeling of mental clarity and calm carry forward even hours after a session.
Slumping can be an outward sign of stress—not to mention that bad posture actually puts more physical stress on your body. “People who are overly stressed often display their worries in their body carriage,” Whitaker says. “Those who are weighed down with stress commonly have a poor posture or struggle with aches and pains in their body. They often slouch when sitting or concave their body inwards with rounded shoulders as they go about their business under the weight of the burdens they carry.” Taking a few seconds when you feel stressed to check your posture and sit up straight (like your mother told you) can help you feel better. “Studies show that poor posture is related to anxiety, depression, helplessness, and irritability, so keeping your chin up and shoulders back will help,” Dr. Serani says. Happy and confident people naturally tend to stand a bit taller. Here are the other stressors you didn’t know you had.

What the Neuro Programmer does (as far as I can tell – access to much of the website requires the purchase of product) is present sound and visuals on the computer screen. The user is meant to passively view and listen to this while their brain is effortlessly programmed to solve whatever problem they are having or improve whatever performance they are interested in.

These brainwaves take a lot of energy to produce and you’ll feel really productive and focused when you’re in this state. Your brain in Beta is actively engaged, aware, and reactive. This is a great state for short-term problem solving or being engaged in exciting activities. It’s not a great state for long-term decision making or really thinking through your actions.
Maya Mendoza is a published author of 3 personal development books. She has run an NLP / EFT Practice for 29 years helping clients transform problems into personal power. Maya is also a accomplished copywriter and well known Digital Marketing & Social Social Media Strategist - Specializing in Google+ for business. She was named "best marketing consultant" in Glasgow, UK in 2013.  
“In order to get into a flow state, you have to calm a part of the brain, the posterior cingulate cortex, which is the source of what brain scientists call the default state, which is the non-focused state,” says Harris. “At any rate, it turns out that Holosync [binaural beats], when you listen to it, [calms that part of the brain] and so does traditional meditation. It’s just Holosync does it faster and more easily and more effortlessly. It turns down the posterior cingulate cortex and it enhances the other part of the brain that, when it’s enhanced, you can easily go into a flow state.”
“Binaural beats are not very noticeable because the modulation depth (the difference between loud and quiet) is 3 db, a two-to-one ratio. (Isochronic tones and mono beats easily have 50 db difference between loud and quiet, which is a 100,00-to-1 ratio). This means that binaural beats are unlikely to produce an significant entrainment because they don’t activate the thalamus.”
Fortunately, the recommendations for exercise in the role of stress management fit with the current health recommendations (12). The proposed physiological adaptations thought to improve the way the body handles stress and recovers from stress can occur with a regular moderate to vigorous aerobic exercise program (12,13,16), such as the recommendations of 150 minutes of moderate-intensity aerobic exercise per week or 75 minutes of vigorous-intensity aerobic exercise per week. If an individual is using exercise as a time-out from stressors, shorter duration activity can serve the purpose, especially when lack of time or fatigue is a concern. Consider an individual who reports significant work-related stress. Breaking the exercise into two 10- to 15-minute sessions, one before work and one at lunch time when possible, can help combat stress throughout the day. Although there is not a lot of research with resistance exercise and stress management, resistance exercise can be used to provide a time-out from one’s stressors. Because resistance training produces different exercise adaptations compared with aerobic exercise, it might not affect the way the body physiologically reacts to stress as aerobic exercise does. However, the acute effect of a time-out to reduce stress can be beneficial. In addition, clients can receive the numerous health benefits associated with resistance training. The resistance exercise prescription for general health benefits of 2 to 3 days of exercise to target all of the major muscle groups performed at a moderate intensity of 8 to 12 repetitions can be recommended.
Cory Allen [b. 1982] is a composer and mastering engineer living in Austin, Texas. His work focuses on the cultivation of human perception with the intent of altering the listener's state of consciousness. Allen's music is deep, patient, meditative, highly-conceptual and often composed by implementing self-organizing structures, rule-based performances, set pitch classes and a wide variety of instruments.
If you can't spend a full hour in meditation, try the 30 minute Theta Standalone Meditation. This track takes you a little deeper into exploring the Theta frequency than the first Theta track, so it can also be a progression if you have used the first Alpha/Theta combination. If you do have a full hour for Theta, use the 60 minute Theta Standalone meditation.

This music encourages a state of delta relaxation. Delta brainwaves are most prevalent during deep, dreamless sleep. The delta state is a mostly unconscious state that is essential to one’s physical, emotional, psychological and spiritual wellbeing. People who are able to achieve a state of delta relaxation through meditation will sometimes describe spiritual encounters and out of body experiences. The delta state is perfect for inducing profound spiritual experiences, healing and deep subconscious repatterning. Delta frequency brainwave entrainment music is also a fantastic cure for insomnia.
Infra-Low brainwaves (also known as Slow Cortical Potentials), are thought to be the basic cortical rythms that underlie our higher brain functions. Very little is known about infra-low brainwaves. Their slow nature make them difficult to detect and accurately measure, so few studies have been done. They appear to take a major role in brain timing and network function. 
When you hit a tuning fork, tuned to a particular sound frequency such as the note B, and hold it close to the strings of a guitar, you will notice that the B string on the guitar will vibrate because it has entrained on to the same frequency of the tuning fork. Interesting enough, the other strings will not vibrate. Only the one with the same tuning as the tuning fork.
♥ Imagine a really bad ringing in your ear and the pain that it brought along or when your ear was throbbing with pain. Can you remember the sound coming from that ear? Probably not, since the pain was probably far more memorable. This sounds very similar to that, but it is not at all painful. Quite a unique experience, really. Try it out, but you need to be wearing earphones and have the volume up.
If you happen to be someone who already knows about the physics of sound, then you’ll know that frequencies of 20 hertz or less cannot be heard by the human ear. So how on earth can we use sound to create frequencies as low as 0.1 hertz, and how will you be able to hear them? This is where the “magic” of binaural beats comes into action. Actually, it’s not magic at all...it’s more physics! If you are feeling a bit adventurous, then click on the following link to find out how binaural frequencies are created. 

Your brain actually has a predominant frequency at which it operates in any given moment; this can be associated with your state of mind. In other words, the emotional state of your mind in any moment, such as feeling happy, sad, frightened, sleepy or excited, can be measured as a frequency and with the right sound technology, you can stimulate the state that you want on command!
Known as audio-visual brainwave entrainment, or AVE, this method involves the simultaneous flashing of light and audible, rhythmic tones using specialized equipment such as the Mind Machine. Also known as the Dream Machine or psycho-Walkman, this lightweight headset lets you experience a wide selection of audio and visual entrainment tracks while having complete mobility.

You’ve heard me talk before about how sound can make a difference to sleep. Patients often tell me that they fall asleep to relaxing music, they seem to find it really helps them let go of active thoughts and quiet their mind—which, like yours probably does, tends to race from one thing to the next all day long (aka I can’t turn off my brain syndrome).
With regard to listening without headphones specifically, you might find it irritating if you are someone who suffers from motion sickness, depending on how the track is created. If you were listening to binaural beats, they really need headphones to work properly. If you are in a room and closer to one speaker you may not even hear binaural beats properly, and if sitting off centre in the room generally, that may have unsettled you if you have motion sickness as the tones try to form a beat in your head. If it was just a standard isochronic tones theta track that shouldn’t be irritating if you have motion sickness.
Doctors and other health professionals have really stressful jobs — often their schedules are demanding, and their work can be emotionally and physically taxing. They must learn how to manage stressful situations at work, and how to unwind when they leave the hospital or clinic. They are also uniquely aware of how crucial stress management is for maintaining health.
“In order to get into a flow state, you have to calm a part of the brain, the posterior cingulate cortex, which is the source of what brain scientists call the default state, which is the non-focused state,” says Harris. “At any rate, it turns out that Holosync [binaural beats], when you listen to it, [calms that part of the brain] and so does traditional meditation. It’s just Holosync does it faster and more easily and more effortlessly. It turns down the posterior cingulate cortex and it enhances the other part of the brain that, when it’s enhanced, you can easily go into a flow state.”

This research investigates the brainwave entrainment process and aims to demonstrate the usefulness of such an approach within the framework of cognitive performance improvements. In the introductory part the theories regarding the neurophysiological structure and the psychological processing of the cognitive system are discussed, for each of their components that are considered to be relevant for this research. The hypothesis states that the stimulation with binaural beats and stroboscopic light, synchronized at 10.2 Hz frequency, will produce a positive change in cognition. The research variables are the cognitive performance (the dependent variable) and the brainwave entrainment (the independent variable). The brainwave entrainment program consists in the synchronized application of Alpha binaural beats and stroboscopic light, at a 10.2 Hz frequency, in a 30 minutes long session. The difference was made by the stroop effect based exercise that was used as a frame. There were 60 participants, divided into two independent samples. The two independent samples t test for the means differences was used in the statistical analysis. The obtained results by evaluations and by statistics confirmed this research's hypothesis, stating that the stimulation with binaural beats and stroboscopic light, synchronized at 10.2 Hz frequency, will produce a positive change in cognition.
Your brainwave activity during sleep is largely distinct from your brain activity when you’re awake. (REM sleep is one exception to this—during REM, your brain is active in ways very much like when you’re awake.) During non-REM sleep, the slower, lower frequency theta and delta waves dominate, compared to the alpha and beta waves that are prominent when you’re alert and active.
The brain is composed of millions of specialized cells called neurons. Neurons send signals to other neurons using electro-chemical messengers called neuro-transmitters that attach to receiving sites located on the neurons themselves. There is a space between the end of the neuron and the receptor called the synaptic gap. As neuro-transmitter chemicals move across this gap, a small electrical charge is created. 

Please note: When you take one earphone out, move it as far away from your ear as possible. With some headphones you may still be able to hear the pulsating sound if the removed headphone is still fairly close to your ear; this is because your brain can still detect the frequency vibration coming from the headphone. In addition, push the earphone that’s still on your ear tightly to your ear, while moving the other earphone as far away as possible.
For example, according to Wikipedia, if you take one frequency in one speaker in a pair of headphones, say, 300Hz, and the other speaker for your other ear has a frequency of 310Hz, the resulting difference of 10Hz would be the rate that the pulse, or beat, plays at. 10Hz (Alpha Waves) would correspond to what the brain puts out when you are generally relaxed. So, in effect, listening to a 10Hz binaural beat for a certain amount of time should take the edge off.
It’s important to keep in mind; a person’s own experiences will be somewhat relative to their starting point. If you are a person who is completely stressed out, burned out, hanging on the ragged edge, experiencing total adrenal fatigue, and you’ve been at that point for awhile, then to you even a small degree of mental quiet and physical relaxation that meditation and brainwave entrainment bring will feel like a tsunami of relief.

Some people believe that using this stuff can be a replacement for meditation. While sitting passively and listening to something that can give you the same effect frequency-wise as meditation, there is still far more benefit to meditating than just entrainment. Meditation and mindfulness allow you to really understand yourself on a level far deeper than technology will bring you.

♥ When I learned about Binaural beats and found out how you can influence your state of mind, I utilized them for most of my college studies. I play 16Hz Beta waves behind my favorite study music. I've been using them for 3 years now and they help me stay focused longer. Just make sure you have quality headphones that can reproduce the frequencies accurately. 2Hz does make a difference with an EQ.


If you search the Internet for "binaural beats" you'll quickly find there's a whole industry built on the idea that listening to binaural beats can produce all kinds of desired effects in your brain. It can alter your mood, help you follow a diet or stop smoking, get you pumped up for a competition, calm you down, put you to sleep, enhance your memory, act as an aphrodisiac, cure headaches, and even balance your chakra. Binaural-Beats.com offers a $30 CD that they call the world's first "digital drug". They claim it can get you drunk without the side effects. I-Doser.com offers a range of music tracks that they say simulates a variety of actual pharmaceuticals, such as Demerol, Oxycontin, and Vicodin. Suffice it to say that no matter what superpower you're looking for, someone on the Internet sells a binaural beat audio file claimed to provide it.

... [9] While entrainment by binaural auditory beats in the alpha frequency has also been shown to enhance creativity, cognition, memory, and an improvement in intelligence tests and achievement tests in learning disabled boys. [10][11][12][13] The gamma-band activity has been shown to involve in a variety of functions such as attention, memory, and consciousness. Current literature suggests that entrainment by gamma beats promotes cognitive flexibility, modulates visual attention, and enhances creativity. ...
That is generally where the science ends and the pseudoscience begins. A number of companies and individuals have then extrapolated from the phenomenon of entrainment to claim that altering the brain waves changes the actual functioning of the brain. There is no theoretical or empirical basis for this, however. Entrainment is a temporary effect on the synchronization of neuronal firing – it does not improve or increase brain functioning, it does not change the hardwiring, nor does it cure any neurological disorder. There is no compelling evidence for any effect beyond the period of entrainment itself.
When signals of two different frequencies are presented, one to each ear, the brain detects phase differences between these signals. "Under natural circumstances a detected phase difference would provide directional information. The brain processes this anomalous information differently when these phase differences are heard with stereo headphones or speakers. A perceptual integration of the two signals takes place, producing the sensation of a third "beat" frequency. The difference between the signals waxes and wanes as the two different input frequencies mesh in and out of phase. As a result of these constantly increasing and decreasing differences, an amplitude-modulated standing wave -the binaural beat- is heard. The binaural beat is perceived as a fluctuating rhythm at the frequency of the difference between the two auditory inputs. Evidence suggests that the binaural beats are generated in the brainstem's superior olivary nucleus, the first site of contra-lateral integration in the auditory system (Oster, 1973). Studies also suggest that the frequency-following response originates from the inferior colliculus (Smith, Marsh, & Brown, 1975)" (Owens & Atwater, 1995). This activity is conducted to the cortex where it can be recorded by scalp electrodes.  
From a brainwave entrainment effectiveness perspective, it’s my understanding that the response from isochronic tones stimulation starts to diminish over 30Hz and that 40Hz is about the limit for using them. So from what I’ve read on the topic a 100Hz beat wouldn’t work, probably because it’s too fast for the brain to process and synchronise with it.

A warning: Be sure to listen to these two tracks no more than twice each per day. Any more and your beta-thought centers can have TOO much energy in them, causing you to feel like you are on a stimulant. Some people may only be able to listen to each track once per day without feeling over-stimulated. That's fine, just go with what works for you. Sometimes less is more when it comes to brainwave entrainment. Don't push too hard trying to force-grow your brain cells. :-)

Another common misconception is that entrainment is going to force your brain into doing something beyond its native capabilities, or at least beyond what it is accustomed to doing. This mistaken belief is often the root that leads to comments like, “When I meditate with LifeFlow my face gets flushed (or my hair vibrates or I develop x-ray vision, or any of the other things we come across). If I meditate without LifeFlow the face flushing doesn’t happen. LifeFlow must be causing it.”


Monaural beats have similarities to binaural beats, but the two separate frequencies are delivered through a pulse pattern and mixed before they reach the listeners ears, resulting in the advantage of being audible without stereo headphones. However, using stereo headphones intensifies the effectiveness of monaural beats and is recommended for the best effect. 
Living in a Mindful Universe relates the emerging view of consciousness that is revolutionizing the scientific community, and is, in many ways, the continuation of Dr. Alexander’s journey since writing Proof of Heaven. This journey parallels an unprecedented shift in the western scientific paradigm that, when fully incorporated, will lead to far more meaning and purpose in our lives.

A large dose of caffeine causes a short-term spike in blood pressure. It may also cause your hypothalamic-pituitary-adrenal axis to go into overdrive. Instead of coffee or energy drinks, try green tea. It has less than half the caffeine of coffee and contains healthy antioxidants, as well as theanine, an amino acid that has a calming effect on the nervous system.

Theta brain waves occur most often in sleep but are also dominant in deep meditation. Theta is known to be a dreamlike state with vivid imagery, intuition and information beyond your normal conscious awareness. This state of mind is excellent for psychic experiences to occur, as well as astral projection and extended remote viewing. To reach this state without falling asleep while meditating takes practice.
This music encourages a state of delta relaxation. Delta brainwaves are most prevalent during deep, dreamless sleep. The delta state is a mostly unconscious state that is essential to one’s physical, emotional, psychological and spiritual wellbeing. People who are able to achieve a state of delta relaxation through meditation will sometimes describe spiritual encounters and out of body experiences. The delta state is perfect for inducing profound spiritual experiences, healing and deep subconscious repatterning. Delta frequency brainwave entrainment music is also a fantastic cure for insomnia.
Entrainment is a phenomenon seen is a wide variety of different natural circumstance. In the field of chronobiology, the study of biological rhythms in living organisms, entrainment is the synchronization of a circadian rhythm with the rhythm of an external pattern, such as the synchronizing of women’s menstrual cycles with the phases of the moon or with one another in a group.
Gamma waves are the most recently discovered brainwave, a discovery made possible by digital EEG technology. Gamma is associated with the integration of information from different areas of the brain, and having a good memory is associated with having a certain baseline of 40 hertz gamma activity. Low gamma activity is associated with learning disabilities and poor memory.
Binaural beats are an auditory illusion where two oscillators, slightly detuned from each other, are played simultaneously with one perceived by each ear. The human brain mixes the audio from each ear, and the listener perceives a "beating" effect that isn't actually there. This is a well-studied phenomenon that has gained the interest of audiologists and neurologists, but it's most famous for being picked up by the alternative medicine community as a way to get high.
“Chronic stress,” however, is not so easily resolved. This type of stress is associated more commonly with negative health concerns. Chronic stress results when there are constant multiple stressors or major life stressors present (4). Money, work, and the economy were the most commonly reported factors contributing to chronic stress in the American Psychological Association’s (APA) 2011 Stress in America™ survey (3). Additional significant stressors include relationships, family responsibilities, family and personal health problems, job stability, and personal safety (3). Major events, such as the death of a loved one, divorce, and moving also can produce chronic stress.
No, it isn’t, at least not in the way these people are thinking. Neither would any other entrainment product you could purchase for that matter. Part of the problem is the proliferation of utter nonsense about brainwave entrainment one can read all over the internet. There is one site in particular that comes to mind, and the contents of that site are often copied by other websites. It is a list of Hz frequencies with their corresponding (alleged) physical effects. The list runs on for many pages. I won’t bother with the link because you can Google it and find it for yourself if you feel the need for a good laugh, but here are some examples regarding meditation and brainwave entrainment from this site:
Some people are more resistant to brainwave entrainment than others and they may need many more sessions for the tones to start taking effect. Experts recommend that you listen to your brainwave entrainment music regularly because the positive impact is cumulative and builds as you listen to it day after day. Once you start feeling the effects, you will want to continue the sessions.
Binaural Beats or “binaural tones” are created by playing slightly different frequencies separately into each ear. The difference between the two frequencies stimulates a response in the brain which correlates with this frequency difference. For example, if we present a 100 Hz tone to the left ear and a 105 Hz tone to the right ear, a frequency of 5 Hz is stimulated. This is what is known as the “frequency following response”.
I have been making relaxation recordings for mental self help and health improvement since 1979. As a pathfinder in EEG ( brainwave monitoring and entrainment ) I understand totally the effects of sound and music on the human mind and body. The recordings offered from your website are without doubt some of the most effective I have ever used and recommend them to my clients whole heartedly
Theta waves have a frequency between 4 and 7.5 hertz, making them slower than more wakeful alpha but faster than the dreamless slumber of delta. Theta brainwaves are the frequencies of nighttime dreams and REM sleep when the brain goes through bursts of activity and eye movement. People also experience theta waves in a state of light sleep, deep relaxation, during meditation and prayer, and when daydreaming. Theta waves produce an experience of inward wakefulness where we become disengaged from the outside world while engaging in inner activity. At the lower frequencies of theta, sleeping states are experienced, and at the higher range of frequency, awake relaxed states are experienced. 
Point #3 can easily be the case if you are still subscribing to the false idea that just listening to an entrainment track is meditation all by itself. Some unscrupulous marketing copy of various entrainment products uses phrases such as; “Our meditation CD meditates you…” which is of course, complete nonsense. I was asked recently to review one marketing ad which claimed, “With our meditation CDs you don’t need to know how to meditate…” This is worse than nonsense, it’s hogwash. That’s like saying, “If you use our wonderful plates and silverware you don’t even need to know how to cook.” If you believe that you’re unlikely to get many takers on your dinner invitations.

This blog was created from an interview with Joseph Kao, creator of iAwake’s Journey to the Center of the Self, and iAwake’s CEO John Dupuy, by Heidi Mitchell, who has been working with John for 11 years as assistant and editor. John introduced her to Integral theory and practice and brainwave entrainment enhanced meditation in 2007. Heidi is also a freelance editor of nonfiction books, blogs, and web sites. She can be reached at www.heidimitchelleditor.com.


You don’t have to run in order to get a runner’s high. All forms of exercise, including yoga and walking, can ease depression and anxiety by helping the brain release feel-good chemicals and by giving your body a chance to practice dealing with stress. You can go for a quick walk around the block, take the stairs up and down a few flights, or do some stretching exercises like head rolls and shoulder shrugs.
A combination of strokes works well to relieve muscle tension. Try gentle chops with the edge of your hands or tapping with fingers or cupped palms. Put fingertip pressure on muscle knots. Knead across muscles, and try long, light, gliding strokes. You can apply these strokes to any part of the body that falls easily within your reach. For a short session like this, try focusing on your neck and head:
Theta waves are associated with ➤ Increased sense of inner peace and emotional stability ➤ Deep relaxation ➤ Improved memory ➤ Heightened intuition and inspiration ➤ Calms the chatter of your mind ➤ Increased psychic abilities and sense of spiritual connection ➤ Speed healing, improved physical healing ➤ More restful sleep ➤ Release beneficial hormones related to health and longevity ➤ Reduce mental fatigue ➤ Reduction of anxiety and stress
Brainwave entrainment is a colloquialism for such 'neural entrainment', which is a term used to denote the way in which the aggregate frequency of oscillations produced by the synchronous electrical activity in ensembles of cortical neurons can adjust to synchronize with the periodic vibration of an external stimuli, such as a sustained acoustic frequency perceived as pitch, a regularly repeating pattern of intermittent sounds, perceived as rhythm, or of a regularly rhythmically intermittent flashing light.
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